Method and device in a coupling node for a telecommunication system

ABSTRACT

The present invention relates to a coupling node (MG 1 ) for coupling of communications in a telecommunication system, comprising networks (N 1,  N 2 ) with different signal formats. The coupling node has switching and trunking functions (CP 21,  CP 23 ) corresponding to the signal formats, and telefunctions, e.g. coders/decoders (F 21 ) and echo cancellers (F 22 ), which the node can couple into a communication by means of a selector (PS 1 ). The functions are supported by printed board assemblies (CB 1 –CB 9 ) in magazines (SR 1 ), and the printed board assemblies have signal processors (DSP 11 –DSP 13 ) with access points (SAP 11 –SAP 14 ). The selector hunts one of the signal processors for handling one of the functions. If the processor has sufficiently free memory space in its data store and in its instruction memory and sufficient processor capacity, this processor is selected. Otherwise a new processor is hunted which is investigated in the same way.

TECHNICAL FIELD

The present invention relates to a device and a method for coupling, ina coupling node in a telecommunication system, a communication andthereby utilizing the processor resources of the coupling node in aneffective manner.

STATE OF THE ART

Telecommunication systems composed by many different types oftelecommunication networks have evolved. The networks can be eithercircuit-switched or packet-switched and can have different types ofsignal formats. The networks including the packet-switched ones arecapable of transferring information in real time and offer in some casesa high quality on services provided, e.g. high availability, goodaudibility and unbroken communication. However, the networks areexpensive for the operators to administrate if the requirement for highquality is to be maintained. These costs can be reduced iftelecommunication networks available so far are replaced with anentirely new packet-switched network. However, this would meandestroying capital. Therefore, efforts have been made to create agateway, through which certain networks can be connected retaining goodquality of the services.

A gateway meeting the above-mentioned demands will become fairlycomplicated. Therefore, it has been important to make the gatewayeffective in the sense that many communications can be coupled through acertain gateway and that its collective resources can be fully utilized.

In an article by Stella Sofianopoulou, “Optimum Allocation of Processesin a Distributed Environment: A Process-to-process Approach” in J. Opl.Res. Soc. Vol. 41, No. 4, pp. 329–337, 1990, it is theoreticallydiscussed how to choose, in a telecommunication system, processors fortreating a number of processes in an optimal manner. The processestreated are, on one hand, connected to coupling of a telecommunication,and, on the other hand, connected to the internal work of theprocessors. More specifically, the article discusses how many processorsare required to effectively take care of a certain number of processes.

The U.S. Pat. No. 6,009,507 describes a computer system with a number ofsignal processors connected to host computer. One of the signalprocessors is subsequently allocated a number of tasks so that theprocessor is fully utilized. When it becomes fully occupied with a task,the system selects a new processor to finish the task.

The international patent application WO 99/35773 describes a system withprocessors, each processing call setups. Data for the setups isdistributed among the processors by a resource handler.

The European patent application EP 0 366 344 B1 describes a system witha plurality of nodes, each having a processor. These are to processenquiries on carrying out certain tasks. The processors have adetermined maximum capacity and a total work load is distributed withthe aid of addresses to the processors. The addresses are entered onto alist, and to avoid overloading the processors, one processor is deletedfrom the list when its load exceeds a threshold value and is re-enteredonto the list when the load has decreased below another threshold value.

SUMMARY OF THE INVENTION

A telecommunication system most often comprises differenttelecommunication networks, connected through nodes. By setup of aconnection in a telecommunication system via these coupling nodes,functions in the node required for the communication, are coupled insequence. The present invention addresses a problem of utilizing theprocessors of the node in an effective manner when handling thesefunctions.

Another problem having been addressed is to utilize the processors inthe node in a flexible manner.

Yet another problem having been addressed is also to utilize thecommunication resources of the node in an effective manner.

The problem is solved by haunting a processor, being a suitablecandidate for handling at least one of the functions in the sequence forthe communication in question. Subsequently it is investigated if theprocessor has sufficient capacity to handle the function. If this is notthe case, a new processor is selected as candidate and investigated in acorresponding manner.

More exactly the problem is solved in that the investigation comprisesestablishing whether the processor has sufficient space in itsinstruction memory and its data store, and that it has sufficientprocessor capacity to carry out the function itself. If this is thecase, i.e. if the function can be allocated to the processor, thecomputer code of the function is loaded into the processor. Theprocessor does not have to be allocated in advance to handle certain ofthe functions, rather the processors in the node can be investigated andthe functions allocated to them as the functions are to be coupled intothe communication. The problem of utilizing the internal communicationresources of the node is solved by selecting the functions so that thecommunication paths between the functions are short.

Thus, an overarching object of the present invention is to couple atelecommunication between different networks via at least one couplingnode and thereby to utilize the processor resources of the nodeeffectively when handling the functions.

Another object is to be able to utilize the processor resources of thenode in a flexible manner.

The nodes are composed of magazines with printed board assemblies,carrying the processors. Thereby, a further object is to be able toutilize the processor capacity of all printed board assemblies as acommon resource in the node to handle the functions.

Yet another object is to be able to utilize the processors in one of thenodes to handle functions from another of the nodes.

Another object is to utilize the internal communication resources of thenode effectively.

The invention has the advantage that the total processor capacity in thenodes are utilized.

Another advantage is that the code for the function in question does nothave to be stored permanently in a processor. Instead, the code can beloaded into the processor when needed for a communication, andthereafter the processor can be used for other functions or otherobjects.

Another advantage is that the number of different types of printed boardassemblies can be reduced, compared to known solutions.

Yet another advantage is that the internal communication resources ofthe nodes are utilized effectively.

The invention will now be described in more detail with the aid ofpreferred embodiments and with reference to the enclosed figures.

DESCRIPTION OF FIGURES

FIG. 1 shows a view of a telecommunication system;

FIG. 2 shows a block diagram of a coupling node;

FIG. 3 shows a flowchart of coupling of a communication from a callingsubscriber to a gateway;

FIG. 4 shows a flowchart of coupling of a telecommunication function inthe communication according to FIG. 3;

FIG. 5 shows a flowchart of coupling of the communication from thegateway to yet another node in the telecommunication system;

FIG. 6 shows a flowchart of coupling of a communication over more thanone gateway in the telecommunication system;

FIG. 7 shows views of parts of the gateway;

FIG. 8 shows a block diagram of the structure of a part of a gateway;

FIG. 9 shows a block diagram of an alternative structure of a part of agateway;

FIG. 10 shows a block diagram of sequential coupling of functions in acommunication;

FIG. 11 shows a block diagram with a hierarchic address;

FIG. 12 shows a block diagram with a hierarchic address;

FIG. 13 shows a flow chart for selection of a function in acommunication;

FIG. 14 shows another flowchart for selection of a function in acommunication;

FIG. 15 shows yet another flowchart for selection of a function in acommunication; and

FIG. 16 shows a flowchart for investigating if a processor can handle afunction.

PREFERRED EMBODIMENTS

FIG. 1 shows, as an example, a view of a part of a telecommunicationsystem TS, comprising a first network N1, being an ATM-network, a secondnetwork N2, being an IP-network, and a third network N3, being aSTM-network. The term ATM here stands for Asynchronous Transfer Mode.The second network 2 is, on one hand, connected to the first network N1through a first gateway MG1 and, on the other hand, connected to thethird network N3 through a second gateway MG2. The telecommunicationsystem also comprises a control server S1 for controlling coupling ofcommunications. The server S1 is connected to the gateway MG1 via aconnection C1 and to the gateway MG2 via a connection C2. The Figurealso shows that further servers, e.g. the server S2, takes part of thetelecommunication system and are in this example connected to thegateway MG1. In the network N1 there is a first subscriber A1 with amobile terminal MP1, which can be coupled to its network through a basestation BS1. The base station is connected to the gateway MG1 via aconnection C31. In the network N2 there is a second subscriber B1 withan orginary, circuit-switched telephone POT1, connected to the gatewayMG1 via a switchboard VX1. The mobile terminal MP1 and the telephonePOT1 can, via the gateway MG1, be connected to each other so that thesubscribers A1 and B1 can talk to each other. In the third network N3there is a third subscriber B2 with a telephone POT2 connected to thesecond gateway MG2 via a switchboard VX2. The subscriber B2 can, via thegateway MG2, be connected to the other subscribers. The structures ofthe gateways MG1 and MG2 and how the coupling is carried out, will bedescribed closer below with the aid of a few embodiments.

FIG. 2 shows the logical structure of the gateway MG1, which has twomain parts, a telefunction part TF1 and an interface block CP2. Thetelefunction part comprises a function block F2 having function deviceswith telefunctions F21–F28 being used in telecommunications. Accordingto the example, the function F21 is a coder/decoder, the function F22 isan echo canceller, the function F23 is a modem, the function F24generates a tone signal ordering a ring signal at a subscriber, thefunction F25 is an announcement function generating spoken standardannouncements, the function F26 makes it possible for a subscriber toleave a voice mail, the function F27 makes conversions between digitalu-law and A-law, and the function F28 attends to conference coupling.The telefunction part TF1 also comprises a signal processing unit CP1,connected to the server S1 by the connection C1, and a first controlunit CC1 for internally in the gateway MG1 control the setup of acommunication. The first control unit CC1 is connected, on one hand, tothe signal processing unit CP1 through an interface 1, and, on the otherhand, to the function block F2 through an interface 2. The functionblock F2 has a second control unit RC2 connected to the function deviceswith the telefunctions F21–F28 through an interface 6 and which controlsthe allocation of the resources in these telefunctions. Each of thetelefunctions are provided in several editions.

The interface block CP2 comprises a physical line interface CP20 havingexternal connections C31, C32, C41 and C42. Included in the block CP2 isa signal format converter CP29 function devices with switching andtrunking functions CP21–CP27 for handling transformations of differentsignal formats of signals being changed via the external connections.The block CP2 also has a third control unit BC3 being connected to, onone hand, the signal format converter CP29 through an interface 7, and,on the other hand, to the second control unit RC2 via an interface I/O2,and is also connected to the first control unit CC1 through an interface3. According to the embodiment, the interface block CP2 has thefollowing switching and trunking functions. The function CP21 is anIP-path selector, the function CP22 terminates IP, TCP and UDP, thefunction CP23 couples ATM-cells, the function CP24 terminates AAL2 (ATMAdaption Layer type 2), the function CP25 couples AAL2-packets, thefunction CP26 couples STM-channels, and the function CP27 terminatesSTM-channels. Also the switching and trunking functions are eachprovided in several editions.

The above stated parts in the gateway MG1 have the following functions.

The signal-processing unit CP1 exchanges signals M1 with the server S1via the connection C1. Among other things the unit handles security andadmission functions, verifies that messages have been received,registers incoming and outgoing messages and announces to the serverwhen changes in status in the gateway have taken place. The signal M1has two parts, one part with an address head and one part with thecontents itself, so-called payload, which is divided into differentpackages. The signal-processing unit CP1 separates the address head on areceived signal and forwards the packets to the first control unit CC1via the interface 1.

The first control unit CC1 receives the signal packets, a signal M2,from the signal-processing unit CP1 and, on the basis thereof, requeststhe required telefunctions F21–F28. The first control unit activates ordeactivates external connections as can be seen from the signal M2, andactivates or deactivates internal connections between the telefunctionsand the external endpoint of the connections.

The second control unit RC2 handles the earlier mentioned telefunctionsF21–F28. The second control unit has information about how many editionsof a certain telefunction that are available. It also has informationabout where the functions are located in a structure of carrierssupporting the function devices, i.e. the control unit has the functionaddresses of the telefunctions. The first control unit CC1 requests viaa signal M3 one of the telefunctions from the second control unit. Thesecond control unit sends a message M4 with a function address for thetelefunction, including information about the location of the functionon the carriers, to the first control unit.

The telefunction part TF1 has, as can be seen from the descriptionabove, the two internal interfaces 1 and 2. The interface 1 is intendedto keep reception and processing of the message M1 itself separated fromthe operations caused by the message. By means of the interface 2, thefirst control unit CC1 can set aside the telefunctions F21–F28 for acommunication or free them whenever they are no longer needed for thecommunication.

In the interface block CP2, the line interface CP20 has different typesof physical interfaces having different transfer rates 1,5, 2, 34 or 155Mbps. The third control unit BC3 can carry out the functions of couplingthe signal format converter CP29 and the switching and trunkingfunctions, of coupling one or more of the telefunctions, as well as ofhunting a free outgoing partial communication to the next node in thecommunication, and establish it. For carrying out these functions, thethird control unit receives a signal M5 from the first control unit withinformation about the incoming connection and about the function addressfor the telefunction to be coupled. The signal M5 can also containinformation about a node to which a partial communication is to becoupled as a continuation of the incoming communication. The thirdcontrol unit BC3 emits a signal M6 to the first control unit CC1, whichsignal can contain, among other things, information about whichcommunication is established to the next node. The signal formatconverter CP29 with the switching and trunking functions CP21–CP28converts incoming signal formats to a common signal format COM1 and alsoreconverts signals from this format to an outgoing signal format for theestablished communication to the next node.

A feature of the gateway MG1 is that the telefunctions in the functionblock F2 remain unchanged and independent of which networks the gatewayis connected to. New functions can be added but the functions themselvesare to remain unchanged over time. Another feature of the gateway isthat any telecommunication network can be connected with the aid of thegateway and new corresponding switching and trunking functions can beadded. It is essential that the telefunctions and the switching andtrunking functions can be stored in the form of hardware or software andcan be stored anywhere within their respective block. Also, the gatewaycan easily be expanded for increased capacity.

The gateway MG1 utilizes the fact that the signals by the connection C31or C32 are connected to their respective switching and trunkingfunctions CP21–CP27, and are subsequently converted to the common signalformat COM1 in the converter CP29. Thereafter, the latter converts thesignals to a signal format which is adapted for that one of theswitching and trunking functions CP21–CP27 which is used, when thesignal is to be forwarded on a partial communication to the next nodevia the connection C41 or c42. Between these two conversions, one ormore of the telefunctions functions F21–F28 can be connected via theconnection I/O2, if this is necessary for the communication.Additionally, a communication, which has already been setup, being inprogress and taking place between the two subscribers A1 and B1, can beopened and one or more further telefunctions can be added. Examples ofsuch functions being added is the conference function F28 for couplefurther subscribers to the communication or the function F25 withstandard messages. All the telefunctions operate in the common signalformat COM1, which is the format that the signals have in the connectionI/O2. When a communication is coupled via the gateway MG1, it can sohappen that none of the telefunctions in the function block F2 needs tobe engaged. However, the transferred signals have different formats atthe inlet and at the outlet, and the incoming signal is converted, asmentioned above, to the common signal format in the converter CP29 to beconverted again to the outgoing signal format.

The gateway MG1 and also the gateway MG2 are from a logical point ofview structured in a way described in connection to FIG. 2, with thethree separate cooperating control units CC1, RC2 and BC3. Thisstructure makes it possible for the gateway to obtain the featuresmentioned above. The common signal format COM1 can be a format knownwithin the technical field, and this is the case in the presentembodiment. Here the format AAL2 is utilized, AAL2 denoting ATM AdaptionLayer type 2, where ATM in turn denotes Asynchronous Transfer Mode. Inconnection with the FIGS. 3, 4, 5 and 6, it will be explained, with theaid of a few embodiments, how the gateway MG1 or MG2 works.

Coupling of a Communication from Subscriber A1 to Gateway MG1

In connection to FIG. 1 it was initially mentioned that the twosubscribers A1 and B1 are connected to each other so that they can talk.A first part in this communication is a call request from the subscriberA1 and coupling of the communication to the gateway MG1 with a signalconverter and coupling of at least one of the telefunctions. In FIG. 3 aflowchart is shown of this first part of the communication.

The subscriber A1 dials in a conventional manner, on his/her mobileterminal MP1, the telephone number to the telephone POT1 of thesubscriber B1 according to block 41 and is connected via the basestation BS1 to the gateway MG1 through the connection C31 according toblock 42. The signalling from the subscriber A1 is coupled through theconnection C1 to the control server S1, block 43. This server detectswhich signal format the subscriber A1 has, in this case compressedspeech, and also detects that the network N1 is an ATM-network, all thisaccording to block 44.

When receiving a call from the subscriber A1, the server receivescertain pieces of information from the subscriber B1, so that the servercan determine the node address for the next node which has to becoupled. Thereby, the server S1 has the information needed to connectthe subscribers A1 and B1. The server sends, through the communicationC1, control signals in the form of the message M1 to the gateway MG1and, more specifically, to the signal-processing unit CP1 according toblock 45. The message M1 is a standard protocol with an address head andan information part divided into different data packets. Thesignal-processing unit CP1 separates the address head and sends theinformation part of the control signals with the message M2 to the firstcontrol unit CC1 according to block 46. This information part isanalyzed by the first control unit with respect to, among other things,information about which telefunctions are required and information aboutthe signal format and a network address ADR2 for the communication fromthe subscriber A1, all this according to block 47. The first controlunit CC1 sends, with the message M3, a request to the second controlunit RC2 for one of the telefunctions, block 48. The mobile terminal MP2of the subscriber A1 sends encoded speech, which has to be decoded to beunderstood by the telephone POT1 of the subscriber B1. Thus, the messageM3 contains a request for the telefunction F21 with a coder/decoderfunction. The second control unit RC2 hunts a free function among thesefunctions according to block 49 and sends its function address ADR11with the message M4 to the first control unit CC1 according to block 50.The first control unit now sends, with the message M5, the functionaddress ADR11 to the available function F21 as well as the networkaddress ADR2 for the incoming communication to the third control unitBC3 according to block 51. The first control unit also sends, with themessage M5, a request for the third unit to couple the network addressADR2 to the address ADR11 for the selected, available coder/decoderfunction F21 according to block 52. The third control unit BC3 couples,according to block 53, the switching and trunking function correspondingto the network address ADR2, in this example the function CP23 forATM-switching. The function CP23 is connected to the telefunction F21according to block 54. Thus, a speech signal TS1, arriving later on theconnection C31 from the subscriber A1, can be received by the switchingfunction CP23 and transformed to the common signal format COM1 in thesignal format converter CP29. Subsequently, the speech signal TS1 can bedecoded via the telefunction F21, operating in the common signal format,before this speech signal is coupled any further.

Coupling of a Further Telefunction in the Gateway MG1

In the example above only one of the telefunctions is coupled, i.e. thecoder/decoder function F21. Often many telefunctions have to be coupledand this is also the case here. The subscriber B1 has the telephonePOT1, which has to have a ring signal, and additionally echoes can occurin the communication. Thus, the tone-generating function F24 and theecho canceller F22 have to be coupled.

When the subscriber A1 made a call, a message was sent to the server S1about the called subscriber B1. Thereby, the server has informationabout the node address NOD 1 of the subscriber B1, and that the latterrequires a ring signal and echo cancelling. This information was passedon to the gateway MG1 with the message M1 and further with the messageM2, and was analyzed in the first control unit CC1. In connection withthe flowchart in FIG. 4, it will be described how the furthertelefunctions are coupled to the communication.

According to block 47 in FIG. 3, the first control unit CC1 analyzes themessage M2. This control unit now requests, according to block 61, thenext telefunction from the second control unit RC2 with the message M3.According to the example, this second telefunction is the telefunctionF24 for tone-generating. The second control unit hunts an available copyof this function according to block 62, and sends, according to block63, the function address ADR3 of the function F24 with the message M4 tothe first control unit CC1. This control unit sends, with the messageM5, the function address ADR3 of the telefunction F24 to the thirdcontrol unit BC3 according to block 64 and also sends, according toblock 65, a request to couple the telefunction F24 into thecommunication. The third control unit BC3 couples, according to block66, this telefunction into the communication, which, according to theabove, is in a stage where it has already been converted to the commonsignal format COM1. The first control unit continues the analysis of themessage M2 and the method according to FIG. 3 is repeated if additionaltelefunctions are to be coupled. This is the case in the presentexample, and also the telefunction F22 for echo cancelling, having afunction address ADR4, is coupled into the communication when this is ofthe common signal format COM1.

It should be noted that the coupling method in the gateway MG1 remainsthe same as that described in the two examples above, even if theincoming communication on the connection C31 would come from some othernode than the base station BS1 with the address NOD2. An example of suchan alternative node is another gateway, e.g. the gateway MG2 with a nodeaddress NOD3. Switching and trunking functions and telefunctions mayhave to be selected differently, but the coupling method itself remainsunchanged.

Coupling from the Gateway MG1 to the Subscriber B1

As mentioned above, the server has information about the calledsubscriber B1, and thereby it can determine the next node to which thecommunication from the subscriber A1 is to be coupled. The next nodewould be, according to an example, the next gateway MG2 but is,according to the present embodiment, the switchboard VX1 having the nodeaddress NOD1 to which the subscriber B1 is connected. How thecommunication from the subscriber A1 is further coupled with a partialcommunication to the switchboard VX1 is described below in connectionwith FIG. 5.

The server S1 has information about that the switchboard VX1 has thenode address NOD1, and sends this information with the message M1 to thesignal-processing unit CP1. This in turn sends the node address NOD1 tothe first control unit CC1 with the message M2 according to block 71.The first control unit sends, with the message M5, the node address NOD1to the third control unit BC3 together with a request to hunt anavailable communication to the node, all this according to block 72. Thethird control unit BC3 hunts an available communication, according tothe example the communication C41, and establishes this according to ablock 73. The third control unit sends, along with a message 6,information about the established communication C41 to the first controlunit CC1, block 74. The first control unit sends, according to block 75,a message to the third control unit BC3 to couple the switching andtrunking function which corresponds to the established communicationC41. The third control unit hunts the function CP21 for IP-routing,having an address ADR21, and couples this function to the most recentlycoupled telefunction in the communication according to block 76. Thesignal format converter CP29 converts the common signal format COM1 to asignal format for the established IP-connection according to block 77.The switchboard VX1 is now connected and generates, upon a signal fromthe telefunction F24, a ring signal to the telephone POT1 according toblock 78. The subscriber B1 receives the call by lifting his/herhandset, block 79.

Coupling of a Communication via a Further Gateway

In connection with a flowchart in FIG. 6, coupling of a communicationbetween the first subscriber A1 and the third subscriber B2 in thenetwork N3 will be briefly described. In the first part of thecommunication from the subscriber A1 to the gateway MG1 only theswitching and trunking functions CP23 for ATM-switching is coupled, andthe communication is converted to the common signal format COM1. Thisfirst step is specified with block 81. Thereafter, the gateway MG1couples the communication further to the gateway MG2 via the network N2according to block 82. This coupling is performed in the similar manneras the coupling to the subscriber B1 according to the description ofFIG. 5. The difference is that none of the telefunctions is coupled inthe gateway MG1 and that the server S1 gives orders for coupling to bedone to the node address NOD3 instead of to the node address NOD1.Another available IP-connection is hunted and also established by thethird control unit BC3. The function CP21, corresponding to thecommunication, is coupled and a re-conversion of the signal format tothe IP-format of the communication is carried out. Then thecommunication is received in the gateway MG2 according to block 83.Thereby the communication is converted from the IP-format to the signalformat COM1, and the three telefunctions F21, F22 and F24 are coupled.It should be noted that this coupling of the telefunctions is not madeuntil now in the gateway MG2. The communication is further coupled tothe switchboard VX2 with the node address NOD4, according to block 84,in a manner similar to that described in connection to FIG. 5. Therebythe communication is converted to STM-format and the switching andtrunking function CP26 is coupled. The returning communication is thencoupled from the subscriber B2 to the gateway MG2 according to block 85,at which the telefunction F21 for coding/decoding is coupled to thecommon signal format COM1 after the conversion from the STM-format. Anavailable communication to the gateway MG1 with a node address NOD5 ishunted by the third control unit in the gateway MG2 and the switchingfunction CP21 is coupled for conversion to the IP-format, all thisaccording to block 86. In the gateway MG1 a conversion is carried out,according to block 87, of the signal format from the IP-format to thecommon signal format COM1. An available communication to the basestation BS1 is hunted and established by the third control unit BC3, theswitching and trunking function CP23 is coupled and the signal format isconverted back to the ATM-format, block 88. The switchings in the aboveexample, carried out in the respective gateway, are shown in more detailby the preceding embodiment.

It should be noted that, in the examples, the different functionsF21–F28 and CP21–CP27 have been retrieved within the gateway at themoment setting about coupling the communication. However, it is possiblefor a gateway to retrieve an edition of a function from another gatewayif all of its own editions of the function in question are busy. Forexample, the gateway MG1 can retrieve the function F21 forcoding/decoding at the gateway MG2 when the gateway MG1 is coupling thecommunication between the subscribers A1 and B1 according to block 49 inFIG. 3.

In the above description an example of the logical structure of thegateway MG1 has been specified. A few examples of coupling ofcommunications in this gateway have also been described. It can be seenthat this coupling requires many steps and in most cases,interconnection of a plurality of the function devices to connect thetelefunctions and the switching and trunking functions. This couplingcan be done effectively and with saving of resources. Thereby, it isimportant that the function devices being coupled in a gateway are closeto each other in the sense that only small resources are consumed toutilize the functions together. Thus, the sheer physical structure ofthe gateway is essential. It is also essential to, in the gateway, in aneasy manner really being able to find these function devices when theyare to be coupled to the communication.

In connection with the FIGS. 7A, 7B and 7C, the structure of thehardware for the gateway MG1 will be described briefly, i.e. thecarriers supporting the function devices of the gateway will bedescribed. FIG. 7A shows the structure of the hardware in a magazine.This has a back plane 101 to which different printed board assembliesare connected. As examples of the printed board assemblies can bementioned a board with the switch core 102 (SCB Switch Core Board), amain board 103 with main processor (GPB General Purpose Board) or board104 having the above mentioned telefunctions F21–F28. The boards are inthe usual manner, according to FIG. 7B, inserted in a magazine SR1, thebackside of which containing the back plane 101. The gateway MG1 iscomposed of one or more magazines, according to the example themagazines SR1, SR2, SR3 and SR4, which are gathered to form a unitaccording to FIG. 7C and the different back planes of which areconnected to each other.

FIG. 8 shows an example of how the function devices for thetelefunctions and the switching and trunking functions are arranged onthe printed board assemblies in the magazine SR1–SR4. A printed boardassembly CBET1 for switching and trunking functions supports thefunctions CP21 for IP-routing, and a printed board assembly CBET23supports the function CP23 for ATM-switching. These two printed boardassemblies are placed in the magazine SR1. The Figure also shows insomewhat more detail how the function CP23 communicates with theconnection C31 and how the function CP21 communicates with theconnection C41. In the same magazine SR1, the printed board assembliesCB1 . . . CB9 are located. The printed board assembly CB1 supportsfunction devices with a number of editions of the coder/decoder F21 inFIG. 2, and the printed board assembly CB9 supports function deviceswith a number of editions of the echo cancelling function F22. Theprinted board assemblies are connected by a packet selector PS1, whichis shown by a solid line 105 between the printed board assemblies andthe packet selector. The Figure also shows some of the printed boardassemblies in more detail. The printed board assembly CB1 is shown withfive signal processors DSP11–DSP15 with connections 106. The signalprocessor DSP11 is shown with four access points SAP11–SAP14. One ormore editions of a telefunction, in the example the coder/decoder F21,are reachable via one of these access points, e.g. the access pointSAP13. The printed board assembly CB9 has four signal processorsDSP91–DSP94, the signal processor DSP91 has four access pointsSAP91–SAB94, and a number of editions of the echo canceller F22 can bereached via the access point SAP92. Signal processors with access pointsare not shown on the printed board assemblies CBET1 or CBET3.

The allocation of the telefunctions of the printed board assemblies,described in FIG. 8, is denoted distributed allocation since eachprinted board assembly supports only one type of telefunction. In acorresponding manner there is an integrated allocation shown in FIG. 9.Similarly to what has been described above, the switching and trunkingfunctions are arranged on the printed board assemblies in the magazineSR1, where the printed board assembly CBET1 supports the function CP21and the printed board assembly CBET3 supports the function CP23. In themagazine SR2, printed board assemblies CB10–CB19 are located. Theprinted board assembly CB10, as well as the printed board assembly CB19,supports a number of editions of the coder/decoder F21 together with theecho cancelling function F22. The printed board assemblies supportsignal processors, of which the processor DSP101 is shown, and thesehave access points of which the access point SAP101 is shown. Theprinted board assemblies are connected to each other via the packetselector PS1.

The allocations of the functions on the printed board assembliesdescribed above can be carried out as a statistical allocation so that acertain printed board assembly always has a certain number of editionsof one of the functions. The integrated allocation can also be carriedout as a dynamic allocation. In this case, the number of editions of oneof the telefunctions on a printed board assembly can vary, and thisnumber is determined by the requirement at hand. This is possible sincethe printed board assemblies can have standard processors, with a codein their memories for several different telefunctions. The resourcehandling becomes more complicated and the control units have to handlethe resources from a plurality of printed board assemblies, like a poolof telefunctions. The control units have a list of available and busyresources, and the list is not connected to any specific telefunction.

As mentioned above, it is essential that the coupling of the differentfunction devices is carried out in a resource-saving manner. Thereby, itis essential to limit the utilization of the communication resourcesneeded for coupling the function devices. When two consecutive functiondevices are located within the same gateway, it is the internalcommunication resources of the gateway which are utilized. The functiondevices are coupled in the communication in sequence, as exemplified inFIG. 10. According to block 91, firstly the switching and trunkingfunction CP23 is connected, thereafter the telefunction F21 according toblock 92, and after that the telefunction F22 is connected according toblock 93, and finally, according to block 94, the switching and trunkingfunction CP21. Closer details concerning similar couplings have beendescribed in connection with FIGS. 3, 4 and 5. The two blocks 92 and 93couple the consecutive function devices for the telefunctions F21 andF22. In order to save resources when making this coupling and to make itfast, units in the gateway are selected according to the followingpriority list, where the first hand choice is point 1, the second handchoice is point 2, etc.:

-   -   1. The function devices are reached via the same access point.    -   2. The function devices are handled by the same signal        processor.    -   3. The function devices are handled by signal processors on the        same printed board assembly.    -   4. The printed board assemblies are located in the same        magazine.

In the cases where a gateway is allowed to retrieve functions fromanother gateway in the telecommunication network TS, the followingfurther step is added to the priority list:

-   -   5. The magazines belong to the same gateway.

When one of the switching and trunking functions and one of thetelefunctions are to be selected after each other, e.g. according to theblocks 91 and 92 or according to the blocks 93 and 94, the followingpriority list is used:

-   -   1. The function devices belong to the same magazine.    -   2. The function devices belong to the same gateway.

This latter priority list can in an obvious manner be extended toinclude also, for example, an attempt to select a common printed boardassembly as a first step.

In connection with the FIGS. 3, 4, 5 and 6, it was mentioned that thedifferent function devices CP21–CP27 and F21–F28 have addresses, e.g.the addresses ADR21 and ADR3, which the control units CC1, RC2 and BC3use for coupling the functions in a communication. More specifically,the addresses are used for being able to find the different functiondevices and for being able to select in accordance with thepredetermined priority lists above. Therefore, the addresses of thefunction devices are hierarchically arranged, as will be described inconnection with the FIGS. 11 and 12. FIG. 11 shows a block diagram witha structure for an address 110 to the telefunctions F21–F28. A block 111specifies the node in which the function is stored, e.g. in the gatewayMG1. A block 112 specifies one of the magazines in this node, e.g. themagazine SR1, a block 113 specifies one of the printed board assembliesin this magazine, e.g. the board CB1, a block 114 specifies one of theprocessors on this board, e.g. the processor DSP11, and a block 115specifies one of the access points, e.g. the access point SAP11. Theaddresses for the telefunctions, e.g. the addresses ADR3 and ADR11, havethis structure. FIG. 12 shows a block diagram with a structure for anaddress 120 to the switching and trunking functions CP21–CP27. A block121 specifies in which node the function is stored, e.g. the gatewayMGW1, a block 122 specifies one of the magazines, e.g. the magazine SR1,and a block 123 specifies one of the printed board assemblies in thismagazine, e.g. the printed board assembly CBET3. Besides the location ofthe functions, the address also specifies, through a block 124, one ofthe connections which might be provided to the function device inquestion and, through a block 125, specifies a user on this link. Theearlier used address ADR21 has this structure.

In connection with the FIGS. 3–6 it has been explained how the addressesare used for coupling a communication. In connection with the FIGS. 13,14 and 15 it will be explained in more detail how the hierarchicstructure of the addresses-according to the FIGS. 11 and 12 is used forconnecting the function devices according to the above mentionedpriority lists.

FIG. 13 starts from a case in which one of the telefunctions is to becoupled in the communication, for example when an edition of thetelefunction F22 according to block 93 in FIG. 10 is coupled. The methodstarts with the second control unit RC2, in a step 130, receiving arequest from the first control unit CC1 to couple the function F22. Thisrequest contains the previous address in the chain, i.e. the address forthe telefunction F21 in block 92. The second control unit investigates,in a step 131, if the access point for the telefunction F21, block 115in FIG. 11, can be used. At this the control unit investigates if anyedition of the telefunction F22 is available from this access point andalso if sufficient processor capacity for handling the function isavailable. If a positive answer Y1 is received, the processor capacityis reserved and the address for the access point is delivered to thefirst control unit CC1 in a block 136. If the answer is negative N1, thesecond control unit RC2 investigates, in block 132, in a correspondingmanner whether the signal processor has an edition of the telefunctionF21, block 114 in FIG. 11, which can be utilized. Upon a positive answerY2, the processor capacity is reserved in a corresponding manner and theaddress, now having another access point, is delivered to the firstcontrol unit, the block 136. Upon a negative answer N2, the procedure isrepeated in a block 133, with an investigation as to whether an editionof the telefunction F22 is available on the printed board assembly,block 113 in FIG. 11, and whether sufficient processor capacity isavailable. Upon a positive answer Y3, capacity is reserved and theaddress is delivered, this time with an access point at anotherprocessor. Upon a negative answer N3, the procedure is repeated one moretime according to a block 134, at which the second control unitinvestigates if the magazine for the telefunction F21 has an edition ofthe telefunction F22 available, with address according to block 112, andif processor capacity is available. Upon a positive answer Y4, theaddress is delivered, as before, according to block 136, to the firstcontrol unit, and the processor capacity is reserved. The address beingdelivered this time is the address for an access point for a processoron a printed board assembly in the magazine supporting the function F21.Upon a negative answer N4, the second control finally investigates if,in the whole node having the address 111, there is an available editionof the function F22 and sufficient processor capacity. Upon a positiveanswer Y5, the address to a found access point in the node is delivered,similarly to what has been described above, according to the block 136.If a negative answer N5 is received, the request from the first controlunit for the telefunction F22 is refused, according to block 137.Consequently, the method has resulted in either an address according tothe block 136 or a refusal according to block 137, and a new inquiry canbe processed according to block 138.

As an alternative to the refusal in the block 137, another node in thenetwork might be hunted which might have an edition of the requestedfunction available. The address for its access point, including theaddress of the node, is supplied to the control unit in question.

An alternative to the method in FIG. 13 will be briefly described inconnection with the flowchart of FIG. 14. The method starts with aninquiry for the telefunction F22 from the first control unit CC1 to thesecond control unit RC2 in a block 140. The second control unitinvestigates, according to block 141, whether the demanded function F22can be found in the same node as the previous telefunction F21. Upon anegative answer N6, the request is refused according to block 147. Upona positive answer Y6, it is investigated whether the function can befound in the same magazine, according to block 142. If thereby anegative answer N7 is received, the address found in the previous step141 is delivered, and the necessary processor capacity is reserved, asspecified by a block 146. Upon a positive answer Y7, it is investigated,according to block 143, whether the function can be found on the sameprinted board assembly. Upon a negative answer N8, the address from theprevious step is delivered, and upon a positive answer Y8, it isinvestigated, according to block 144, whether the function can be foundon the same processor. A negative answer N9 results in the address fromthe previous step 143 being delivered. A positive answer Y9 results inan investigation according to block 145 as to whether an edition of thedemanded telefunction F22 can be found at the same access point as theprevious telefunction F21. Upon a negative answer N10, the address foundin the previous step is delivered, and upon a positive answer Y10, therecently found address is delivered and processor capacity is reserved,see block 146. A new request can be processed according to block 148. Ifthe telefunction can be retrieved from another node, the method isinitiated by a corresponding request.

In connection with FIG. 15 an example will be briefly described, showinghow the priority list is used to find a suitably placed edition of theswitching and trunking function CP21 in FIG. 10, which has an hierarchicaddress with a structure having been shown in FIG. 12. In this case itis the third control unit BC3 which receives a request from the firstcontrol unit CC1 for an address to the demanded function. This should belocated as close as possible to the preceding function, i.e. thetelefunction F22. The method is initiated with a request from the thirdcontrol unit in a block 150. In a block 151 the third control unit BC3investigates whether there is any available edition of the function CP21in the node in which the telefunction F22 is located and whether thereis necessary processor capacity. Upon a negative answer N11, the requestis refused according to block 157. Upon a positive answer Y11, thecontrol unit BC3 investigates, according to block 152, whether there isany available edition of the function CP21 in the same magazine as thetelefunction. Upon a negative answer N12, the third control BC3delivers, according to block 156, the address for the edition of thefunction CP21 which was found in block 151. The receiver is, as before,the first control unit CC1. Upon a positive answer 12, the third controlunit investigates, according to block 153, whether there is an editionof the function CP21 on the printed board assembly which supports thetelefunction F22. Upon a negative answer N13, the third control unit BC3delivers the address to the edition which was found according to block152. Upon a positive answer Y13, the address found according to block153 is delivered to the first control unit CC1 together with informationabout reserved processor capacity, block 156. According to block 158, anew request can be processed.

In connection with FIG. 2, the gateway MG1 was described being used asan example of a coupling node, which can have hierarchically structuredcarriers. It should be noticed that the coupling node could be effectedin another way. One example of such an execution is that the converterCP29 in FIG. 2 is effected similarly to one of the telefunctions in thefunction block F2. Another example of the execution of the coupling nodeis that all the functions, the telefunctions F21–F28 as well as theswitching and trunking functions CP21–CP27, are gathered in one unit andcontrolled from one single central control unit. This gives a somewhatsimpler but less flexible structure of the coupling node.

It has been described above how the telefunctions as well as theswitching and trunking functions are selected for a communication. Ithas also been shown how a suitable candidate among the processors isselected to handle the functions. It is important that the totalprocessor capacity in a node is utilized effectively. The choice of aprocessor is therefore carried out in a flexible way, after which it ischecked if the selected candidate has sufficient capacity in differentrespects. If the capacity of the candidate is insufficient, a newcandidate is selected which in turn is checked as well. This will bedescribed in more detail below.

In connection with FIG. 8 and FIG. 9, the printed board assembliesCB1–CB9 and CB10–CB19 have been described, each of which being able tohandle a plurality of the telefunctions F21–F28 simultaneously. Eachprinted board assembly has a plurality of processors, e.g. theprocessors DSP91–DSP94, and each processor can handle a plurality of thetelefunctions. The total processor capacity from all the printed boardassemblies in, for example, the node MG1 can be used effectively if thisprocessor capacity is utilized as a common, flexible resource in thenode. Therefore, a printed board assembly in the node cannot have apredetermined number of editions of a certain telefunction stored.

Neither can the allocation of the telefunctions to certain printed boardassemblies and their processors remain unchanged, since it is notpossible to know in advance how many editions of each of thetelefunctions are needed in the node and the demand can vary with time.Therefore, the processors are in general not preloaded with computercodes for the telefunctions, rather the processors are usually handledas common resources in the following way.

-   -   1. The instruction memory in each processor is handled as a        resource, since each processor can handle a number of the        telefunctions but in most cases not all of these. A processor        which would handle all of the telefunctions would need a large        instruction memory, which is expensive and occupies a large        space on the printed board assembly.    -   2. The processor capacity, expressed in, for example, MIPS (Mega        Instructions Per Second) for each processor, is handled as a        resource. This makes it possible to fully use the capacity, and        at the same time exceeding the available capacity is avoided.    -   3. The data store for each processor is handled as a resource to        be able to fully use this memory and at the same time avoid        exceeding available memory capacity. Both the allocation of the        data code for the telefunctions and the number of editions of        each telefunction in the node depend on the requirements present        on a certain occasion. A method for allocating the telefunctions        so that the total processor capacity in the node is utilized        will be described below in connection with the flowchart in FIG.        16.

When the first control unit CC1 is to allocate one of the telefunctionsF21–F28 to the communication, it sends a request for this to the secondcontrol unit RC2 according to the previous description. This request isthe starting point for the method according to step 160. The data codefor the telefunction can be stored on, for example, one of the printedboard assemblies CB1–CB9, but, alternatively, also in a centralprocessor in the node MG1 or in another node in the telecommunicationsystem TS. According to a step 161, the second control unit RC2 selectsone of the processors, for example according to the earlier describedpriority list with the items 1–5. The second control unit checks,according to step 162, on one hand, the size of the processor capacityavailable in the selected processor, and, on the other hand, the size ofthe processor capacity needed for processing the telefunction inquestion. Thereafter, the control unit compares whether the capacity ofthe processor is sufficient according to step 163. If the answer isnegative according to an alternative NO, the second control unit RC2selects a new processor in the step 161. If the answer is positiveaccording to an alternative YES, the second control unit checks, on onehand, the amount of data store needed for the telefunction in question,and, on the other hand, how much memory capacity the processor canprovide, all this according to step 164. Thereafter, according to step165, the second control unit RC2 compares whether the available memorycapacity is enough. If the answer is negative, according to analternative NO, the control unit selects a new processor according tothe step 161. If the answer is positive, according to an alternativeYES, the second control unit investigates, in step 166, whether the datacode for the telefunction in question is available on the processor. Ifthis is not the case, according to an alternative NO, the second controlunit RC2 checks, according to a step 169, whether there is room for thedata code in the instruction memory. If the answer to this question isnegative, according to an alternative NO, a new processor is selected inthe step 161. If the answer is positive, according to an alternativeYES, the processor capacity, the data store and the instruction memoryare reserved in a step 170. Thereafter, the data code is loaded,according to a step 171, and the allocation of the telefunction to thecommunication is completed, according to a step 168. In the step 166,the second control unit investigated whether the data code for thetelefunction in question was available in the processor. If this is thecase, according to an alternative YES, the second control unit RC2reserves the processor capacity and the data store according to a step167. Thereby, the allocation of the telefunction to the communication iscompleted according to step 168.

In order to be able to carry out the method described above, the secondcontrol unit RC2 has access to the following information concerning,among other things, the processors on the different printed boardassemblies.

-   -   1. The hierarchic address for the processors.    -   2. Telefunctions possible to provide by the different printed        board assemblies.    -   3. The amount of available processor capacity which the        different processors can provide.    -   4. The amount of data store available for the different        processors.    -   5. The amount of instruction memory available for the different        processors.    -   6. The amount of processor capacity required for the different        telefunctions.    -   7. The amount of data store required for the different        telefunctions.    -   8. The amount of instruction memory required for the different        telefunctions.

In connection with FIG. 9, the printed board assemblies CB10 and CB19have been described. These printed board assemblies support thecoder/decoder F21 together with the echo canceller function F22.According to an alternative to the method in FIG. 16, not only onetelefunction at a time is handled when a processor is to be found havingsufficient capacity. Instead, at least two of the telefunctions arehandled together, e.g. the functions F21 and F22. These two functionscan be expected to be utilized at a plurality of call setups. If the twofunctions are executed together, less processor capacity is consumedthan if they are executed separately.

According to a further alternative, the capacity of the hunted processoris compared with threshold values instead of being compared with thecapacity required for the function in question. The threshold values arechosen so that, if the capacity of the processor reaches the thresholdvalues, this capacity will be sufficient for each of the functions.

1. A coupling node in a telecommunication system for coupling ofcommunications in the telecommunication system, said coupling nodecomprising: connections for the communications and a connection for aserver; function devices with functions intended for the communications,the functions being supported by carriers, wherein the function devicesare by the carriers arranged in a hierarchic structure; processorssupported by the carriers; a selector device being arranged to couple,after a signal from the server, at least a first of the functions,wherein the selector device is arranged to, at the coupling of at leastone of the functions, on one hand hunt for a first one of the processorsbeing a candidate for handling said at least one of the functions, onthe other hand investigate whether the hunted processor has resources inthe form of sufficient free space in its data store and in itsinstruction memory and sufficient processor capacity for the handling,the coupling node comprises internal communication resources for thefunction devices; the function devices each having their own hierarchicaddress, corresponding to the hierarchic structure of the functiondevices, and the selector device being arranged, by means of thehierarchic addresses to select two of the function devices for one ofthe communications within the communication consecutive of saidfunctions in such a way that the amount of internal communicationresources being utilized for connecting said two function devices, islimited.
 2. The coupling node in a telecommunication system according toclaim 1, wherein the selector device has information on which resourcesare required for the handling of the function, and is arranged tocompare said resources of the hunted processor with the correspondingresources for the handling of the function.
 3. The coupling node in atelecommunication system according to claim 1, wherein the selectordevice is arranged to hunt for a second one of the processors if saidfirst processor lacks resources for the handling.
 4. The coupling nodeaccording to claim 1, wherein the carriers for the function devicescomprise at least one magazine with printed board assemblies, which areconnected to each other via a back plane in the magazine and whichsupport the processors with access points, the selector device beingarranged to select the two function devices in one and the samemagazine.
 5. The coupling node according to claim 4, wherein one of theprinted board assemblies supports function devices having only one typeof functions.
 6. The coupling node according to claim 4, wherein one ofthe printed board assemblies supports function devices having at leasttwo different types of functions.
 7. The coupling node according toclaim 1, wherein the carriers for the function devices comprise at leastone magazine with printed board assemblies, which are connected to eachother via a back plane in the magazine and which support the processorswith access points, the selector device being arranged to select the twofunction devices in one and the same printed board assembly.
 8. Thecoupling node according to claim 1, wherein the carriers for thefunction devices comprise at least one magazine with printed boardassemblies, which are connected to each other via a back plane in themagazine and which support the processors with access points, theselector device being arranged to select the two function devices in oneand the same processor.
 9. The coupling node according to claim 1,wherein the carriers for the function devices comprise at least onemagazine with printed board assemblies, which are connected to eachother via a back plane in the magazine and which support the processorswith access points, the selector device being arranged to select the twofunction devices so that they will have the same access point in one ofthe signal processors.
 10. The coupling node according to claim 1,wherein the carriers for the function devices comprise at least onemagazine with printed board assemblies, which are connected to eachother via a back plane in the magazine and which support the processorswith access points, the selector device being arranged to select the twofunction devices, in the first place, in the same printed board assemblyand, in the second place, in the same magazine.
 11. The coupling nodeaccording to claim 1, wherein the carriers for the function devicescomprise at least one magazine with printed board assemblies, which areconnected to each other via a back plane in the magazine and whichsupport the processors with access points, the selector device beingarranged to select the two function devices, in the first place so thatthey can be reached via the same access point, in the second place sothat they can be handled by one and the same processor, in the thirdplace so that they can be handled by the processors in the same printedboard assembly, and in the fourth place so that the printed boardassemblies are placed in the same magazine.
 12. A method for a couplingnode in a telecommunication system for coupling of a communication, thecoupling node comprising connections for communications and a connectionfor a server; function devices with functions, intended for thecommunications and supported by carriers; and processors supported bythe carriers, the method comprising: selecting at least one of thefunctions after a signal from the server; hunting for a first processoras a candidate for handling of said function; and investigating whetherthe hunted processor has sufficiently free space in its data store andin its instruction memory and sufficient processor capacity for saidhandling, wherein the coupling node comprises internal communicationresources for the function devices; arranging the function devices in ahierarchic structure by means of the carriers for the function devices;allocating to each of the function devices a hierarchic address,corresponding to the hierarchic structure of the function devices; andselecting, by means of the hierarchic addresses, two of the functiondevices for one of the communications within the communicationconsecutive of said functions in such a way that the amount of internalcommunication resources being utilized for connecting said two functiondevices, is limited.
 13. The method for a coupling node according toclaim 12, further comprising comparing, in the selector device, saidresources in the hunted processor with the corresponding resourcesrequired for handling the function.
 14. The method for a coupling nodeaccording to claim 12, further comprising hunting, by the selectordevice, for a second processor if said first processor lacks resourcesfor the handling.
 15. The method according to claim 12, wherein thecarriers for the function devices comprise at least one magazine withprinted board assemblies, which are connected to each other via a backplane in the magazine and which support processors with access points,the method comprising selection of the two function devices in the samemagazine.
 16. The method according to claim 15, wherein one of theprinted board assemblies supports function devices having only one typeof functions.
 17. The A method according to claim 15, wherein one of theprinted board assemblies supports function devices having at least twodifferent types of functions.
 18. The method according to claim 12,wherein the carriers for the function devices comprise at least onemagazine with printed board assemblies, which are connected to eachother via a back plane in the magazine and which support processors withaccess points, the method comprising selection of the two functiondevices in the same printed board assembly.
 19. The method according toclaim 12, wherein the carriers for the function devices comprise atleast one magazine with printed board assemblies, which are connected toeach other via a back plane in the magazine and which support processorswith access points, and wherein the method comprises selecting the twofunction devices in the same signal processor.
 20. The A methodaccording to claim 12, wherein the carriers for the function devicescomprise at least one magazine with printed board assemblies, which areconnected to each other via a back plane in the magazine and whichsupport processors with access points, and wherein the method comprisesselecting the two function devices so that they will have the sameaccess point in one of the processors.
 21. The A method according toclaim 12, wherein the carriers for the function devices comprise atleast one magazine with printed board assemblies, which are connected toeach other via a back plane in the magazine and which support processorswith access points, and wherein the method comprises selecting the twofunction devices, in the first place, in the same printed board assemblyand, in the second place, in the same magazine.
 22. The method accordingto claim 12, wherein the carriers for the function devices comprise atleast one magazine with printed board assemblies, which are connected toeach other via a back plane in the magazine and which support processorswith access points, and wherein the method comprises selecting the twofunction devices, in the first place so that they are reached via thesame access point, in the second place so that they are handled by thesame processor, in the third place so that they are handled byprocessors in the same printed board assembly, and in the fourth placeso that the printed board assemblies are placed in the same magazine.